The present disclosure relates to a motor and a washing machine using the same.
A washing machine is an apparatus that washes laundry using washing water and friction. In a drum washing machine, laundry is placed inside a drum which is oriented sideways in the washing machine, and a washing operation is performed through rising and falling motions of the laundry as the drum rotates at a low speed. Here, the drum lies sideways and its opening faces the front of the washing machine. A motor is located at the rear of the washing machine to deliver a rotational force to the drum. Since the motor is provided at the rear side of the drum washing machine, this increases the horizontal length of the washing machine, and thus increases the volume of the washing machine. When the volume of the washing machine increases, a larger installation space is required, which reduces user satisfaction of the washing machine, especially if indoor space is at a premium.
An outer rotor type motor is used as a motor for the drum washing machine. The motor includes a stator fixed on the rear side of a tub and including a plurality of circularly arranged coils, and a rotor connected to the drum and including a circularly disposed permanent magnet. An electromagnetic force generated between the coils and the permanent magnet causes the rotor to rotate. The rotational force of the rotor is determined by the intensity of the electromagnetic force. The electromagnetic force is determined by the intensity of the magnetic field of the permanent magnet and the intensity of the electric field generated by the coils. Therefore, it is preferable for the magnetic field of the permanent magnet to be as strong as possible, and for a high current to flow through the coils to generate a strong electric field. If a motor generates a strong electromagnetic force, its size does not need to be large.
In some conventional washing machines, the permanent magnet is a ferrite magnet, and the coils are made of copper. However, a recent increase in the price of copper has considerably increased the manufacturing costs of these washing machines.
Also, since a ferrite magnet provides a small magnetic field, a large ferrite magnet is required to generate a sufficient rotational force to drive the drum of the washing machine. To support a permanent magnet having a large volume and heavy weight, a pocket for receiving the permanent magnet is manufactured separately in the rotor, and the permanent magnet is inserted into the pocket. However, this manufacturing method not only complicates a manufacturing process of an injected material, but also increases manufacturing costs even more due to a difficulty of a molding process. Also, because the volume and mass of the motor increases, the rotation load also increases when the motor rotates, which generates noise and vibration in the motor.
Also, since a separate rotator core provided by injection is used, there is magnetic flux leakage, which deteriorates an output. To reduce the output deterioration, the structure of the rotor must become even more complicated, causing the mechanical strength of the rotor to be reduced and manufacturing costs to increase.